21587149 has 2 divisors, whose sum is σ = 21587150. Its totient is φ = 21587148.

The previous prime is 21587131. The next prime is 21587171. The reversal of 21587149 is 94178512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13089924 + 8497225 = 3618^2 + 2915^2 .

It is a cyclic number.

It is not a de Polignac number, because 21587149 - 2¹⁷ = 21456077 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21587549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10793574 + 10793575.

It is an arithmetic number, because the mean of its divisors is an integer number (10793575).

Almost surely, 2^21587149 is an apocalyptic number.

It is an amenable number.

21587149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21587149 is an equidigital number, since it uses as much as digits as its factorization.

21587149 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 37.

The square root of 21587149 is about 4646.1972622780. The cubic root of 21587149 is about 278.4400884506.

It can be divided in two parts, 21587 and 149, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 21587149 in words is "twenty-one million, five hundred eighty-seven thousand, one hundred forty-nine".